<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./js/vue.js"></script>
</head>

<body>
    <div id="app">
        <p>{{msg}}</p>
        <input type="text" v-model="msg">
		<p v-once >{{msg}}</p>

    </div>
	
	<script type="text/javascript">
		let vm=new Vue({
			el:"#app",
			data:{
				msg:"123"
			}
		})
	</script>

</body>

</html>